KERUI Wireless Calling System,for Coffee shop. Wireless Service Paging System. Pack of 20 pcs Service Buzzers and 1 pc Signal Receiver of KR-C1999 Compatible with 999 wireless transmitters, name of transmitter can be edited,in our shop,there are some buttons you can choose,also we can customize the product for you as your needs. Easily Installed-can be installed on each table,when the guest needs any service, he or she just press the button, his or her table number will show on the receiver with reminder sound ,then the waiters will go and offer best service in time. Highly anti-interference and stable performance,4 types of working mode setting and 8 types calling mode setting for you choose. Receiver display pager Working Voltage:DC 12V/2A;transmitter button working voltage:Two CR2016 3V lithium batteries.Transmission distance: 100m(328 ft) in the open air,but if there are some barriers,the distance will reduce a half,while the distance is too long and signal not so stable,may be you can add a signal repeater,this ASIN(B00V7WP1BI)FYI. Wireless Paging System-It is widely used for restaurants, bars, Internet cafes, tea house, cafe,hospitals, clinics, nursing homes, nursing homes, Banks, schools, factories, construction sites, hotels, hotel rooms, enterprises and institutions and residential buildings and other places of call services